Watching YouTube footage used to be Sonny Bill Williams' only training tool when he took up boxing.

And the man who kept appearing in his search results was a certain "Francois Botha".

Now the code-hopping Williams wants to kick-start his own boxing highlights reel - with Botha as his first big-name victim.

Williams, 27, became a big fan of South Africa's Botha - dubbed the "White Buffalo" - when he took the unorthodox step of preparing for his first three pro fights by surfing through YouTube for hours.

These days, ex-All Black Williams takes his boxing a lot more seriously - and he had to after agreeing to take on his hero in their WBA International heavyweight title bout in Brisbane on Friday night.

"Hopefully I earn his respect but I won't be asking for an autograph," laughed Williams after weighing in at 107kg on Thursday before Botha, 44, tipped the scales at 115.25kg.

Williams (5-0 record) stared down Botha (48-8-3) after their weigh-in - but the Sydney Roosters NRL player already had a good look at the South African on his computer.

"When I first got into the boxing game, I watched a lot of fights on YouTube and obviously when you type in 'boxing', Frans' name comes up a lot," Williams said.

"I have seen a lot of his fights and studied him a lot. I have got a gameplan but one punch could change that."

The quietly spoken Williams was in contrast to a boisterous Botha who took over their pre-fight media conference, even interrupting the weigh-in for Quade Cooper who will appear on Friday night's undercard.

"If he wins and bulks up, I am willing to fight him," Botha laughed, pointing to the Wallabies five-eighth.

Williams compared taking on the hulking Botha with tackling a 115kg Springbok prop.

"They breed them big over there and they just keep coming," he smiled.

"I will hit him with all I have got ... it will be a massive challenge.

"What's the worst that could happen - get knocked out? At least I tried.

"He's trying to play mind games but I have been involved in professional sport for 10 years so I know how all that works.

"I hopefully do all my talking in the ring."

In contrast to Williams, Cooper curiously didn't bother doing any research ahead of his professional boxing debut against car crash assessment officer Barry Dunnett, who has a Muay Thai background.

"I haven't seen any of his fights and I am not going to bother watching them," Cooper said.

"I am just going to follow the gameplan that I have."

The usually reserved Cooper (87.1kg) looked like he wanted to start the fight early in an intense face to face with Dunnett (88.6kg) after their weigh-in.

But clearly Dunnett wasn't intimidated.

"He doesn't look like an overly confident person - he couldn't even show up to this on time," Dunnett said.

"I don't go back to a $100,000 rugby contract after this so I will be going out there fighting hard."

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